兰坪—思茅中生代盆地的特征及构造演化

CHARACTERISTICS AND TECTONIC EVOLUTION OF THE LANPING-SIMAO MESOZOIC BASIN

兰坪—思茅中生代盆地发育于滇西古特提斯多岛洋构造格局基础之上,其形成演化与特提斯—三江造山带的构造演化密切相关。中三叠世,伴随中特提斯洋开启,地壳拉张裂陷,兰坪—思茅中生代盆地开始形成。晚三叠世末—早侏罗世,由于受中特提斯关闭引起的造山运动的影响,下侏罗统普遍缺失。从中侏罗世开始,由于新特提斯洋开启,盆地再次下沉接受中侏罗统—白垩系的沉积。喜马拉雅造山运动期间,该区地壳大面积隆升,兰坪—思茅盆地遭受强烈变形,形成具有明显特征的对冲构造,继而在中生代盆地基础上叠加了新生代的拉分盆地。构造演化控制了盆地的沉降作用、沉积作用、火成活动和构造格架。

The Lanping-Simao Mesozoic Basin is a sedimentary basin which was developed based on the Paleo-Tethys multi-island ocean framework, and its formation and evolution are closely related to the tectonic evolution of the Tethys-Sanjiang orogenic belt. The prototype basin was formed during the Middle Triassic accompanying the open of the Mid-Tethys Ocean. The closing of the Mid-Tethys made the crust deformed and the Lower Jurassic missed universally during the end of the Late Triassic to the Early Jurassic. The Neo-Tethys opened during the Middle Jurassic. It made the basin subside again and accept the Middle Jurassic-Cretaceous deposit. Himalayan orogenic movement made the Neo-Tethys closed, and the crust uplifted large scale when the basin was deformed to form fractures, folds and characteristic ramp structures. Then the Cenozoic pull-apart basin superposed on the Mesozoic basin. The tectonic evolution controlled the subsidence, sedimentation, pyrogenesis and structure framework of the basin.